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  • Pulley Tightening Torque

    Discussion in 'Calculations' started by anhlt7337, Aug 17, 2021.

    1. anhlt7337

      anhlt7337 Member

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      Hi everyone!
      I'm newbie
      I got a problem when calculate bolt tightening torque for clamp pulley (belt transmission of motorcycle) as bellow picture:
      Please explain to me how to calculate: how much bolt axial tension (clamp force) for 01 bolt is enough?
      Material:
      - Pulley: S45C
      - Bolt: S45C
      - Hub mounting(Thread tap hole): Aluminium (A356)

      Thanks you very very much!
      upload_2021-8-17_9-23-37.png
       
      Last edited: Aug 17, 2021
    2.  
    3. s.weinberg

      s.weinberg Well-Known Member EngineeringClicks Expert

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      I don't think the information shown is particularly useful for answering your question.
      The tightening torque affects the axial force, and prevents loosening. It depends on the materials and lubricant used, and what forces are trying to loosen the bold. So long as your screws don't loosen, I think what matters, as far as the loads shown, is shear yield of the screws, which is probably far in excess of what you need.

      A quick Google turns up about 28 Nm as a reasonable torque spec for your bolts, in most conditions. I'd consider that a safe starting point for what you're doing, unless it's a super-critical application, in which case, you need an expert.
       
    4. anhlt7337

      anhlt7337 Member

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      thanks you for you answer. But in my opinion, the pulley can be slip cause by belt traction (shear force) so, we have to calculate tightening bolt torque to make a axial force enough to against this shear force.
       
    5. chrstopher007

      chrstopher007 Member

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      As= Tensile stress area for fastener or area of material (in2, mm2). To find the tensile strength of a particular bolt, you will need to refer to Mechanical.
       
    6. Erich

      Erich Well-Known Member

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      Draw a Free body diagram and indicate all the forces acting. Then we can discuss.
       

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